Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
2001-06-13
2003-01-14
Adams, Russell (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S034000
Reexamination Certificate
active
06505938
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a projection display that incorporates transmissive and reflective light modulators for modulating different color components.
2. Description of the Related Art
In order to form an output image on a display screen, primary color components, such as red, green and blue color components, are processed and then synthesized by a projection display to result in an output light beam that is projected by a projection lens.
Referring to
FIG. 1
, a first conventional projection display
1
is used to separate an input light beam from a light source into first, second and third color components
101
,
102
,
103
, such as red, green and blue color components, which are subsequently and respectively modulated by first, second and third light valves
181
,
182
,
183
. The projection display
1
includes a first dichroic mirror
11
, a second dichroic mirror
12
, a reflective mirror
13
, a first polarization beam splitter prism
14
, a second polarization beam splitter prism
15
, a third polarization beam splitter prism
16
, a color synthesizing prism
17
, the first, second and third light valves
181
,
182
,
183
, and a projection lens
19
.
In operation, when the S-polarized first, second and third color components
101
,
102
,
103
are received by the first dichroic mirror
11
, the first and third color components
101
,
103
will be reflected by the first dichroic mirror
11
in a transverse direction toward the second dichroic mirror
12
, whereas the second color component
102
will be allowed to pass through the first dichroic mirror
11
toward the reflective mirror
13
. The second dichroic mirror
12
separates the first color component
101
, which is allowed to pass therethrough toward the first polarization beam splitter prism
14
, from the third color component
103
, which is reflected by the second dichroic mirror
12
in a transverse direction toward the third polarization beam splitter prism
16
. The reflective mirror
13
reflects the second color component
102
toward the second polarization beam splitter prism
15
.
The first polarization beam splitter prism
14
directs the first color component
101
toward the first light valve
181
. When activated, the first light valve
181
modulates the. first color component
101
, and changes the polarization state of the first color component
101
from the S-polarization state to the P-polarization state. The first light valve
181
then reflects the modulated first color component
101
back to the first polarization beam splitter prism
14
. The first polarization beam splitter prism
14
directs the modulated first color component
101
to the color synthesizing prism
17
.
The second polarization beam splitter prism
15
directs the second color component
102
toward the second light valve
182
. When activated, the second light valve
182
modulates the second color component
102
, and changes the polarization state of the second color component
102
from the S-polarization state to the P-polarization state. The second light valve
182
then reflects the modulated second color component
102
back to the second polarization beam splitter prism
15
. The second polarization beam splitter prism
15
directs the modulated second color component
102
to the color synthesizing prism
17
.
The third polarization beam splitter prism
16
directs the third color component
103
toward the third light valve
183
. When activated, the third light valve
183
modulates the third color component
103
, and changes the polarization state of the third color component
103
from the S-polarization state to the P-polarization state. The third light valve
183
then reflects the modulated third color component
103
back to the third polarization beam splitter prism
16
. The third polarization beam splitter prism
16
directs the modulated third color component
103
to the color synthesizing prism
17
.
The color synthesizing prism
17
receives the modulated P-polarized first, second and third color components
101
,
102
,
103
from the first, second and third polarization beam splitter prisms
14
,
15
,
16
, and provides the modulated P-polarized first, second and third color components
101
,
102
,
103
to the projection lens
19
so as to form an output image on a display screen (not shown).
It is noted that the conventional projection display
1
includes a large number of components, and is both bulky and heavy. In addition, the conventional projection display
1
utilizes three polarization beam splitter prisms and a color synthesizing prism, which are relatively expensive, thereby increasing the cost of the projection display
1
. Moreover, aside from the high precision requirement and the difficult manufacturing process for the color synthesizing prism, the cementing planes of the four right-angle prisms that constitute the color synthesizing prism have an adverse affect on the resolution of the output image projected by the projection display
1
. Furthermore, if the four right-angle prisms are imprecisely joined, the modulated color components cannot be properly combined to form a proper and high quality output image on the display screen.
Referring to
FIG. 2
, a second conventional projection display
2
is also capable of separating an input light beam from a light source into first, second and third color components
201
,
202
,
203
, such as red, green and blue color components, which are subsequently modulated prior to reception by a projection lens (not shown) . The projection display
2
includes a first total internal reflection prism
21
, a second total internal reflection prism
22
, a third total internal reflection prism
23
, a dichroic color splitting prism
24
, a first digital micro-reflective light valve
25
, and a second digital micro-reflective light valve
26
. A total reflection interface
221
, in the form of a clearance, is provided between the first and second total internal reflection prisms
21
,
22
. A color splitting interface
222
is present between the second total internal reflection prism
22
and the dichroic color splitting prism
24
.
In operation, when the first, second and third color components
201
,
202
,
203
are received by the first total internal reflection prism
21
, they will be reflected by the first total internal reflection prism
21
toward the second total internal reflection prism
22
. The first color component
201
will be reflected by the color splitting interface
222
and then by the total reflection interface
221
so as to be received by the first digital micro-reflective light valve
25
. When activated, the first digital micro-reflective light valve
25
modulates the first color component
201
, and reflects the modulated first color component
201
back to the total internal reflection interface
221
. The modulated first color component
201
is then reflected by the total internal reflection interface
221
to the color splitting interface
222
, and is further reflected by the color splitting interface
222
to pass through the second total internal reflection prism
22
, the first total internal reflection prism
21
, and the third total internal reflection prism
23
in sequence. On the other hand, the second and third color components
202
,
203
will pass through the second total internal reflection prism
22
and the dichroic color splitting prism
24
so as to be received by the second digital micro-reflective light valve
26
. When activated, the second digital micro-reflective light valve
26
modulates the second and third color components
202
,
203
, and reflects the modulated second and third color components
202
,
203
such that the latter can pass through the dichroic color splitting prism
24
, the second total internal reflection prism
22
, the first total internal reflection prism
21
, and the third total internal reflection prism
23
in sequence. The modulated first, second and third color components
201
,
202
,
Chan Sheng-Hsiung
Chuang Fu-Ming
Tsai Han-Wen
Adams Russell
Prokia Technology Co., Ltd.
Sever Andrew
Trop Pruner & Hu P.C.
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